The present invention relates to a manufacturing method of a semiconductor device and, in particular, to technology effective in applying to a cleaning method for removing contaminants attached onto a surface of a semiconductor wafer.
Since various kinds of contaminants, such as particles (fine particles), organic substances, and metal, attach onto and remain on a surface of a semiconductor wafer (hereinafter simply referred to as a wafer) in manufacturing steps of a semiconductor device, cleaning processing is essential in which these contaminants are removed using a cleaning liquid (a chemical solution or pure water). However, in a step of processing the surface of the wafer with the cleaning liquid, there occur such problems that the wafer is charged due to various causes, and that thereby a semiconductor element formed on the wafer is damaged or destroyed by static electricity.
In Patent Document 1 (Japanese Patent Laid-Open No. 2007-221026), disclosed is wafer cleaning technology that prevents static electricity charged on a wafer from being transmitted through a cleaning liquid at the moment when the cleaning liquid is discharged and then being partially discharged. Specifically, when cleaning the wafer while scanning a nozzle for supplying the cleaning liquid, first, discharge of the cleaning liquid is started from an area other than an element formation region of the wafer (a peripheral portion of the wafer), and subsequently, the nozzle for supplying the cleaning liquid is moved to the element formation region to clean it. According to this method, since the cleaning liquid is discharged to the element formation region after discharged to the peripheral portion of the wafer to discharge the static electricity, a semiconductor element formed in the element formation region is not affected by the static electricity.
In Patent Document 2 (Japanese Patent Laid-Open No. 2008-159789), disclosed is a single wafer type cleaner in which chuck pins that hold a wafer are comprised of conductive resin of a lower resistance (not more than 100 kΩ), and in which pipes that supply a cleaning liquid to a front surface and a back surface of the wafer are comprised of conductive resin of a lower resistance (not more than 100Ω) for the purpose of discharging static electricity charged on the wafer and static electricity generated by a flow of the cleaning liquid.
In Patent Document 3 (Japanese Patent Laid-Open No. 1997-092635), disclosed is a cleaner in which a carrier that holds a wafer is comprised of a conductive material whose volume resistivity is not more than 1×1015 Ω/cm, and in which charging of the carrier is prevented by grounding it to eventually suppress charging of the wafer in contact with the carrier.